The present invention is related to low temperature heat transfer fluids.
Heat transfer fluids for use at low temperatures have frequently been based on ethylene glycol due to its high boiling point, its miscibility with water and its moderate flammability and explosive properties. However, in recent years some questions have been raised concerning its toxicity. This has led to investigation of heat transfer fluids based on substances other than ethylene glycol.
One approach to avoiding the use of ethylene glycol is to simply substitute propylene glycol for ethylene glycol. However, since propylene glycol has higher viscosity than ethylene glycol, fluids prepared in this way are not entirely acceptable.
U.S. Pat. No. 3,607,756, issued to Phillips on Sep. 21, 1971 teaches that a heat transfer fluid comprising propylene glycol, propylene carbonate and water is useful for certain heat transfer applications. However, there remains a need for effective heat transfer fluids possessing low toxicity.